Thomi Pilioura

An Overview of Standards and Related Technology in Web Services

The Internet is revolutionizing business by providing an affordable and efficient way to link companies with their partners as well as customers. Nevertheless, there are problems that degrade the profitability of the Internet: closed markets that cannot use each others services; incompatible applications and frameworks that cannot interoperate or built upon each other; difficulties in exchanging business data. Web Services is a new paradigm for e-business that is expected to change the way business applications are developed and interoperate. A Web Service is a self-describing, self-contained, modular application accessible over the web. It exposes an XML interface, it is registered and can be located through a Web Service registry. Finally, it communicates with other services using XML messages over standard Web protocols. This paper presents the Web Service model and gives an overview of existing standards. It then sketches the Web Service life-cycle, discusses related technical challenges and how they are addressed by current standards, commercial products and research efforts. Finally it gives some concluding remarks regarding the state of the art of Web Services.

Scenarios of using web services in M-commerce

The web service paradigm is a promising technology for developing applications in open, distributed and heterogeneous environments. The proliferation of this new technology has coincided with significant advances in the hardware and software capabilities of mobile devices. Due to the great benefits that come with the web service technology, such as interoperability, dynamic service discovery and reusability, there is a strong interest in making mobile devices capable of providing and consuming web services over wireless networks. This paper describes several scenarios of using web services in mobile devices and identifies their advantages, issues and challenges.

Unified publication and discovery of semantic Web services

The challenge of publishing and discovering Web services has recently received lots of attention. Various solutions to this problem have been proposed which, apart from their offered advantages, suffer the following disadvantages: (i) most of them are syntactic-based, leading to poor precision and recall, (ii) they are not scalable to large numbers of services, and (iii) they are incompatible, thus yielding in cumbersome service publication and discovery. This article presents the principles, the functionality, and the design of PYRAMID-S which addresses these disadvantages by providing a scalable framework for unified publication and discovery of semantically enhanced services over heterogeneous registries. PYRAMID-S uses a hybrid peer-to-peer topology to organize Web service registries based on domains. In such a topology, each Registry retains its autonomy, meaning that it can use the publication and discovery mechanisms as well as the ontology of its choice. The viability of this approach is demonstrated through the implementation and experimental analysis of a prototype.

PYRAMID-S: a scalable infrastructure for semantic Web service publication and discovery

Web services enhance current Web functionality by altering its nature from document to service-oriented. As the number of Web services increases, it becomes increasingly important to provide a scalable infrastructure of registries that allows both developers and end-users to perform discovery of semantic Web enabled services. The discovery of services needs to be based on QoS characteristics in order to enable result ranking and service selection. Current Web service publication and discovery mechanisms, such as UDDI, either address these issues partially or not at all. In this paper, we build on the enabling technologies of Web services, peer-to-peer and semantic Web in an attempt to address all these important dimensions of service publication and discovery. More specifically, we use a hybrid peer-to-peer topology to organize registries based on domains. In such a model, each registry retains its autonomy, meaning that it can use the publication and discovery mechanisms as well as the ontology of its choice.

E-Services: Current Technology and Open Issues

The Internet changes the way business is conducted. It provides an affordable and easy way to link companies with their incorporating trading and distribution partners as well as customers. However, the Internets potential is jeopardized by the rising digital anarchy: closed markets that cannot use each others services; incompatible applications and frameworks that cannot interoperate or build upon each other; difficulties in exchanging business data; lack of highly available servers and secure communication. One solution to these problems is a new paradigm for e-business in which a rich array of modular electronic services (called e-services) is accessible by virtually anyone and any device. This new paradigm is currently the focus of the efforts of many researchers and software vendors. This paper presents the e-services architecture, its advantages as opposed to todays applications and gives an overview of evolving standards. It then presents the related technical challenges, the way some of them are addressed by existing technology and the remaining open issues.

Using Web Services for supporting the users of wireless devices

The Web Service paradigm is currently considered as the most promising and rapidly evolving technology for developing applications in open, distributed and heterogeneous environments. The proliferation of this new technology has coincided with significant advances in the hardware and software capabilities of wireless devices. The combination of the two worlds (i.e. making wireless devices capable of providing and consuming Web Services) is considered of major importance to the computing industry for the forthcoming years. This paper describes two scenarios of using Web Services in wireless devices, identifies their advantages and supporting technologies. A reference architecture for the use of Web Services in the wireless world is proposed. Finally, the results of the performance evaluation of an experimental setup are presented.

Distributed technologies CORBA, Enterprise JavaBeans, Web services: a comparative presentation

This paper presents a comparison of several technologies for developing distributed applications. The specific technologies into consideration are CORBA, Enterprise JavaBeans and Web Services. The comparison involves both qualitative factors, like data representation, transfer protocols and discovery services, as well as quantitative factors, which measure the performance of the models into consideration. In order to facilitate the comparison, an application has been developed that implements exactly the same functionality in all three technologies.

Seamless Federation of Heterogeneous Service Registries

Web service technology extends the existing web infrastructure by transforming it from a repository of documents to a source of services. As the number of web services increases, the provision of the appropriate service publication and discovery framework is of paramount importance for exploiting the full potential of the web service technology. This paper presents the principles, the functionality and the design of PYRAMID-S, a scalable framework for unified publication and discovery of semantically enhanced services scattered around heterogeneous Registries. It uses a hybrid peer-to-peer topology to organize Registries based on domains. In such a topology, each Registry retains its autonomy, meaning that it can use the publication and discovery mechanisms as well as the ontology of its choice. Furthermore, the discovery of services is based on QoS characteristics in order to enable service selection.

A Unified Approach for the Discovery of Web and Peer-to-Peer Services

As the Web service technology matures, other computing paradigms such as peer-to-peer gradually adopt the service-oriented approach and are beginning to expose functionality as services. Hence there is a need for integration of these heterogeneous services, for the development of service-oriented applications. The first step to accomplish this is to establish a unified approach for service discovery. In this paper, we briefly present a query language along with its enacting service search engine which is used for effectively discovering Web and P2P services in a unified manner

Design issues and alternatives for setting up real-time interactive Telelectures

The continuous technological advances in networking and multimedia systems stimulate the integration o f real-time interactive telelectures as an important service o f a telelearning environment. Real-time interactivity is a key technological factor for the success and dissemination o f telecourses. CUI (Centre Universitaire lnformatique) at the universiO~ o f Geneva and GMD (the German National Institute for Information Technology) at Bonn ran real-time interactive telelectures on a regular basis for one academic year. In this paper we describe the experience we gained out o f the experiment, design issues we investigated and technical problems we had to deal with.